air condition DODGE NEON 2000 Service User Guide

AMBER ABS WARNING LAMP
The amber ABS warning lamp is located in the
instrument cluster. The purpose of the warning lamp
is discussed in detail below.
When the ignition key is turned to the ON posi-
tion, the amber ABS warning lamp is lit until the
CAB completes its self-tests and turns off the lamp
(approximately 4 seconds). The amber ABS warning
lamp will illuminate when the CAB detects a condi-
tion that results in the shutdown of ABS function.
The CAB sends a message to the mechanical instu-
ment cluster (MIC) instructing it to turn on the
amber ABS warning lamp.
Under most conditions, when the amber ABS warn-
ing lamp is on, only the ABS function of the brake
system is affected; The electronic brake distribution
(EBD), the base brake system and the ability to stop
the vehicle are not affected.
WHEEL SPEED SENSOR (WSS)
At each wheel of the vehicle there is one wheel
speed sensor (WSS) and one tone wheel (Fig. 3) (Fig.
4) (Fig. 5) (Fig. 6). Each front wheel speed sensor is
attached to a boss in the steering knuckle. The front
tone wheel is part of the driveshaft outboard con-
stant velocity joint. The rear wheel speed sensor is
mounted to the rear disc brake adapter. The rear
tone wheel is an integral part of the rear wheel hub
and bearing.
The wheel speed sensor operates on electronic
energy supplied by the CAB and outputs a square
wave signal whose current alternates between two
constant levels. Its frequency is proportional to the
speed of the tone wheel. The output is available as
long as the sensor is powered and its state (high or
low) corresponds to the presence or absence of tone
wheel teeth. The output signal is sent to the CAB. If
a wheel locking tendency is detected by the CAB, it
will then modulate hydraulic pressure via the HCU
to prevent the wheel(s) from locking.
Correct ABS operation is dependent on accurate
wheel speed signals. The vehicle's tires and wheels
all must be the same size and type to generate accu-
rate signals. Variations in tire and wheel size can
produce inaccurate wheel speed signals.
Improper speed sensor-to-tone wheel clearance can
cause erratic speed sensor signals. The speed sensor
air gap is not adjustable, but should be checked when
applicable. Wheel speed sensor-to-tone wheel clear-
ance specifications can be found in the SPECIFICA-
TIONS section within this section in this service
manual group.
ELECTRONIC BRAKE DISTRIBUTION
Vehicles equipped with ABS use electronic brake
distribution (EBD) to balance front-to-rear braking.The EBD is used in place of a rear proportioning
valve. The EBD system uses the ABS system to con-
trol the slip of the rear wheels in partial braking
range. The braking force of the rear wheels is con-
trolled electronically by using the inlet and outlet
valves located in the integrated control unit.
Upon entry into EBD the inlet valve for the rear
brake circuit is switched on so that the fluid supply
from the master cylinder is shut off. In order to
decrease the rear brake pressure, the outlet valve for
Fig. 3 Left Front Wheel Speed Sensor
1 ± LEFT FRONT WHEEL SPEED SENSOR
2 ± TONE WHEEL
Fig. 4 Right Front Wheel Speed Sensor
1 ± RIGHT FRONT WHEEL SPEED SENSOR
2 ± TONE WHEEL
PLBRAKES 5 - 69
DESCRIPTION AND OPERATION (Continued)

ABS ELECTRONIC DIAGNOSIS
The following information is presented to give the
technician a general background on the diagnostic
capabilities of the ABS system. Complete electronic
diagnosis of the ABS system used on this vehicle is
covered in the Chassis Diagnostic Procedures manual.
Electronic diagnosis of the ABS system used on
this vehicle is performed using the DRBIIItscan
tool. The vehicle's scan tool diagnostic connector is
located under the steering column lower cover, to the
left side of the steering column (Fig. 10).
ABS SELF-DIAGNOSIS
The ABS system is equipped with a self-diagnosis
capability, which may be used to assist in the isola-
tion of ABS faults. The features are described below.
START-UP CYCLE
The self-diagnosis ABS start-up cycle begins when
the ignition switch is turned to the ON position.
Electrical checks are completed on ABS components,
including the CAB, solenoid continuity, and the relay
system operation. During this check the amber ABS
warning lamp is turned on for approximately 5 sec-
onds and the brake pedal may emit a popping sound,
moving slightly when the solenoid valves are
checked.
DRIVE-OFF CYCLE
The first time the vehicle is set in motion after an
ignition off/on cycle, the drive-off cycle occurs. This
cycle is performed when the vehicle reaches a speed
of approximately 20 kph (12 mph.).²The pump/motor is briefly activated to verify
function. When the pump/motor is briefly activated, a
whirling or buzzing sound may be heard by the
driver. This sound is normal, indicating the pump/
motor is running.
²The wheel speed sensor output correct operating
range is verified.
ONGOING TESTS
While the system is operating, these tests are per-
formed on a continuous basis:
²solenoid continuity
²wheel speed sensor continuity
²wheel speed sensor output
DIAGNOSTIC TROUBLE CODES (DTC's)
Diagnostic trouble codes (DTC's) are kept in the
controller's memory until either erased by the techni-
cian using the DRB, or erased automatically after
3500 miles or 255 ignition key cycles, whichever
occurs first. DTC's are retained by the controller
even if the ignition is turned off or the battery is dis-
connected. More than one DTC can be stored at a
time. When accessed, the number of occurrences
(ignition key cycles) and the DTC that is stored are
displayed. Most functions of the CAB and the ABS
system can be accessed by the technician for testing
and diagnostic purposes using the DRB.
LATCHING VERSUS NON-LATCHING DIAGNOSTIC TROUBLE
CODES
Some DTC's detected by the CAB are ªlatchingº
codes. The DTC is latched and ABS braking is dis-
abled until the ignition switch is reset. Thus, ABS
braking is non-operational even if the original DTC
has disappeared. Other DTC's are non-latching. Any
warning lamps that are turned on are only turned on
as long as the DTC condition exists; as soon as the
condition goes away, the amber ABS warning lamp is
turned off, although, in most cases, a DTC is set.
INTERMITTENT DIAGNOSTIC TROUBLE CODES
As with virtually any electronic system, intermit-
tent electrical problems in the ABS system may be
difficult to accurately diagnose. Most intermittent
electrical problems are caused by faulty electrical
connections or wiring. A visual inspection should be
done before trying to diagnose or service the antilock
brake system; this will eliminate unnecessary diag-
nosis and testing time. Perform a visual inspection
for loose, disconnected, damaged, or misrouted wires
or connectors; include the following components and
areas of the vehicle in the inspection.
(1) Inspect fuses in the power distribution center
(PDC) and the wiring junction block. Verify that all
fuses are fully inserted into the PDC and wiring
Fig. 10 ABS System Diagnostic Connector Location
1 ± DRIVER AIRBAG MODULE
2 ± PASSENGER AIRBAG MODULE
3 ± DATA LINK CONNECTOR
PLBRAKES 5 - 75
DIAGNOSIS AND TESTING (Continued)

SERVICE DIAGNOSIS±CLUTCH INTERLOCK/UPSTOP SWITCH
CONDITION POSSIBLE CAUSES CORRECTION
ENGINE STARTER
WON'T CRANK
WHEN CLUTCH
PEDAL IS
PRESSED TO THE
FLOORClutch interlock switch does not have
continuity when plunger is depressed 1.25
mm (1.30 in.)Defective switch or open wiring circuit.
Replace switch if necessary.
Interlock switch plunger is not depressed
when clutch pedal is pushed to the floorFloor mat interferes with clutch pedal
movement or clutch pedal bracket is bent.
Problem is related to other components in
the starting circuit.Check other components in the starting
circuit. Refer to Battery/Starting/Charging
System in Group 8.
SPEED CONTROL
DOES NOT
TERMINATE WHEN
CLUTCH PEDAL IS
DEPRESSED BY AT
LEAST 33 mm (1.30
in.)Upstop switch circuit is closed when clutch
pedal is depressed, or harness is shorted.Refer to Upstop Switch Electrical Test in
this group. Repair wiring or replace switch
assembly as necessary.
Other speed control system failure. Refer to Group 8H, Speed Control for
further diagnosis and testing procedures.
REMOVAL AND INSTALLATION
CLUTCH CABLE
REMOVAL
(1) Disconnect both battery cables.
(2) Remove battery clamp and remove battery
from vehicle.
(3) Remove battery tray from mount bracket.
(4) Remove bellhousing cap (Fig. 7).
(5) Disconnect clutch cable from transaxle housing
and clutch release lever as shown in (Fig. 7).
(6) Disconnect the clutch cable from the clutch
pedal spacer (Fig. 8).
NOTE: Use care when handling clutch cable
assembly. Improper handling can cause adjuster
mechanism to come apart, making re-installation
difficult.
(7) Carefully guide cable through pedal assembly
bore and remove from vehicle.
INSTALLATION
(1) Insert the clutch pedal end of the cable into
position and connect the cable to the clutch pedal
spacer as shown in (Fig. 8).
(2) Verify adjuster mechanism function as follows:
(a) With slight pressure, pull the clutch release
lever end of the cable to draw the cable taut.(b) Push the clutch cable housing toward the
dash panel (With less than 25 lbs. of effort, the
cable housing should move 30-50mm.). If the cable
Fig. 7 Clutch Cable at Transaxle
1 ± CLUTCH CABLE
2 ± TRANSAXLE
3 ± BELLHOUSING CAP
PLCLUTCH 6 - 7
DIAGNOSIS AND TESTING (Continued)

COOLING SYSTEM
TABLE OF CONTENTS
page page
DESCRIPTION AND OPERATION
COOLING SYSTEM........................1
COOLANT...............................2
COOLANT PERFORMANCE..................2
COOLANT RECOVERY SYSTEM..............3
ENGINE THERMOSTAT.....................3
RADIATOR..............................3
RADIATOR COOLING FAN MODULE...........3
COOLING SYSTEM PRESSURE CAP..........4
RADIATOR HOSES AND CLAMPS............5
WATER PUMP...........................5
AUTOMATIC TRANSMISSION OIL COOLER.....6
ACCESSORY DRIVE BELTS.................6
ENGINE BLOCK HEATER...................6
DIAGNOSIS AND TESTING
COOLING SYSTEM DIAGNOSIS..............7
ENGINE THERMOSTAT TESTING............14
ACCESSORY DRIVE BELT DIAGNOSIS........14
WATER PUMP DIAGNOSIS................15
COOLING SYSTEM FLOW CHECK...........15
ELECTRIC FAN MOTOR TEST...............15
COOLANT CONCENTRATION TESTING........15
TESTING COOLING SYSTEM FOR LEAKS.....15
PRESSURE CAP TO FILLER NECK SEAL
PRESSURE RELIEF CHECK...............16
PRESSURE TESTING COOLING SYSTEM
PRESSURE CAP.......................16
LOW COOLANT LEVEL AERATION...........17
DEAERATION...........................17
TEMPERATURE GAUGE INDICATION.........17
ENGINE BLOCK HEATER..................17
SERVICE PROCEDURES
COOLANT LEVEL CHECKÐROUTINE.........17COOLANTÐADDING ADDITIONAL...........18
COOLANT LEVELÐSERVICING.............18
COOLING SYSTEMÐDRAINING.............19
COOLING SYSTEMÐREFILLING............19
REMOVAL AND INSTALLATION
WATER PUMP..........................19
WATER PUMP INLET TUBE................20
ENGINE THERMOSTAT....................20
RADIATOR.............................21
RADIATOR DRAINCOCK...................22
COOLING FAN MODULE...................22
COOLANT RECOVERY CONTAINER..........23
ENGINE BLOCK HEATER..................24
ACCESSORY DRIVE BELTS................24
AUTOMATIC BELT TENSIONER & PULLEY....26
DISASSEMBLY AND ASSEMBLY
COOLING FAN MODULE...................26
CLEANING AND INSPECTION
WATER PUMP..........................28
ACCESSORY DRIVE BELT INSPECTION.......28
COOLING SYSTEM CAP...................28
COOLING SYSTEM CLEANING..............28
RADIATOR FLUSHING....................28
REVERSE FLUSHING.....................29
CHEMICAL CLEANING....................29
ADJUSTMENTS
BELT TENSION..........................29
SPECIFICATIONS
COOLING SYSTEM CAPACITY..............30
TORQUE SPECIFICATIONS.................30
SPECIAL TOOLS
COOLING..............................30
DESCRIPTION AND OPERATION
COOLING SYSTEM
The cooling system consists of an engine cooling
module, thermostat, coolant, and a water pump to
circulate the coolant. The engine cooling module may
consist of a radiator, electric fan motor, fan, shroud,
coolant reserve system, transmission oil cooler, hoses,clamps, air conditioning condenser and transmission
oil lines.
²When the Engine is cold: The thermostat is
closed and the cooling system has no flow through
the radiator. The coolant flows through the engine,
heater system and bypass.
²When the Engine is warm: Thermostat is open
and the cooling system has flow through the radiator,
engine, heater system, and bypass.
PLCOOLING SYSTEM 7 - 1

protection. MopartAntifreeze or the equivalent is
recommended for best engine cooling without corro-
sion. When mixed only to a freeze point of -37ÉC
(-35ÉF) to -59ÉC (-50ÉF). If it looses color or becomes
contaminated, drain, flush, and replace with fresh
properly mixed solution.
COOLANT RECOVERY SYSTEM
This system works in conjunction with the radiator
pressure cap to utilize thermal expansion and con-
traction of the coolant to keep the coolant free of
trapped air. The system provides space for expansion
and contraction. Also, the system provides a conve-
nient and safe method for checking and adjusting the
coolant level at atmospheric pressure without remov-
ing the pressure cap. It also provides some reserve
coolant to compensate for minor leaks and evapora-
tion or boiling losses. All vehicles are equipped with
this system (Fig. 2).
Refer to Coolant Level Check, Deaeration, and
Pressure Cap sections for operation and service.
ENGINE THERMOSTAT
The engine thermostat is located on the front of
the engine (radiator side) in the thermostat housing/
engine outlet connector. The thermostat has an air
bleed (vent) located in the flange and a O-ring for
sealing incorporate on it. There is a relief in the ther-
mostat housing/outlet connector for the O-ring.
The engine thermostat is a wax pellet driven,
reverse poppet choke type. It is designed to provide
the fastest warm up possible by preventing leakage
through it and to guarantee a minimum engine oper-
ating temperature of 88 to 93ÉC (192 to 199ÉF). Also,
the thermostat will automatically reach wide open, to
accommodate unrestricted flow to the radiator astemperature of the coolant rises in hot weather to
around 104ÉC (220ÉF). Above this temperature the
coolant temperature is controlled by the radiator, fan,
and ambient temperatureÐnot the thermostat.
A thermostats primary purpose is to maintain
engine temperature in a range that will provide sat-
isfactory engine performance and emission levels
under all expected driving conditions. It also provides
hot water (coolant) for heater performance. It does
this by transferring heat from engine metal and
automatic transmission oil cooler (if equipped) to
coolant, moving this heated coolant to the heater core
and radiator, and then transferring this heat to the
ambient air.
RADIATOR
The radiator is a down-flow type (vertical tubes)
with design features that provide greater strength,
as well as sufficient heat transfer capabilities to keep
the engine coolant within operating temperatures.
The radiator functions as a heat exchanger, using
air flow across the exterior of the radiator tubes. This
heat is then transferred from the coolant and into
the passing air.
The radiator has an aluminum core with plastic
tanks. Although stronger than brass, plastic tanks
are subject to damage by impact. Always handle radi-
ator with care.
RADIATOR COOLING FAN MODULE
The radiator cooling fan is a single speed electric
motor driven fan. The fan module includes an electric
motor, fan blade, and a support shroud that is
attached to the radiator (Fig. 3).
Fig. 2 Coolant Recovery System
1 ± RECOVERY HOSE
2 ± ENGINE COOLANT RECOVERY CONTAINER
3 ± PRESSURE CAP
Fig. 3 Radiator Fan
1 ± SCREWS
2 ± LOWER MOUNTS
3 ± FAN MOTOR ELECTRICAL CONNECTOR
PLCOOLING SYSTEM 7 - 3
DESCRIPTION AND OPERATION (Continued)

Radiator cooling fan control operation is accomplished
two ways. The fan always runs when the air condition-
ing compressor clutch is engaged. In addition to this
control, the fan is turned on by the temperature of the
coolant which is sensed by the coolant temperature sen-
sor which sends the message to the Powertrain Control
Module (PCM). The PCM turns on the fan through a
fan relay by grounding the relay's coil. The fan relay is
located in the Power Distribution Center (PDC) (Fig. 4).
Refer to the label beneath the PDC cover for location of
fan relay.
The PCM will actuate the fan relay whenever the A/C
clutch is engaged regardless of coolant temperature and
vehicle speed. If the A/C clutch is not engaged, the PCM
will actuate the fan relay when the coolant temperature
reaches approximately (97É C) 207É F and turns off the
fan relay when the coolant temperature drops to
approximately (94ÉC) 201É F. The fan relay is also
turned off when the vehicle speed is above approxi-
mately 100 Km/h (62 MPH). Refer to Group 8W, Wiring
Diagrams for circuity provided.
If the cooling fan is inoperative or a Diagnostic
Trouble Code (DTC) related to fan control has been
set, refer to the appropriate Powertrain Diagnostic
Manual for complete diagnostic procedures.
COOLING SYSTEM PRESSURE CAP
The cooling system pressure cap is located on the cool-
ant outlet housing near the front of the cylinder head.
The cooling system will operate at higher than atmo-
spheric pressure. The higher pressure raises the coolant
boiling point, allowing increased radiator cooling capac-
ity. The pressure cap will release cooling system pres-
sure in a range of 97±124 kPa (14±18 psi).
A vent valve located in the center of the cap allows
a small amount of coolant flow from the coolant
reserve system (CRS) tank. This valve is spring
loaded in the closed position. However, it must be
free to open during system cool-down.If the valve is
stuck shut, the radiator hoses will collapse on
cool-down. Clean the vent valve (Fig. 5) to
ensure proper sealing function.
There is a gasket in the cap that seals to the top of
the filler neck so that vacuum is maintained to draw
coolant back into the system from the coolant reserve
system (CRS) tank.
Fig. 4 Power Distribution Center (PDC)
RADIATOR COOLING FAN OPERATION CHART
Cooling Fan Control
A/C Off
Fan On: 97É C (207É F)
Fan Off: 94É C (201É F)Vehicle Speed >
100 Km/h (62
MPH)
A/C On
Fan OnÐregardless of coolant temperature or vehicle
speed.
Fig. 5 Cooling System Pressure Cap
1 ± PRESSURE RATING
2 ± FILLER NECK SEAL
3 ± PRESSURE VALVE
4 ± VACUUM VENT VALVE (SHOWN IN SEALING POSITION)
7 - 4 COOLING SYSTEMPL
DESCRIPTION AND OPERATION (Continued)

RADIATOR HOSES AND CLAMPS
WARNING: IF VEHICLE HAS BEEN RUN RECENTLY,
WAIT 15 MINUTES BEFORE WORKING ON VEHI-
CLE. RELIEVE PRESSURE BY PLACING A SHOP
TOWEL OVER THE CAP AND WITHOUT PUSHING
DOWN ROTATE IT COUNTERCLOCKWISE TO THE
FIRST STOP. ALLOW FLUIDS TO ESCAPE
THROUGH THE OVERFLOW TUBE AND WHEN THE
SYSTEM STOPS PUSHING OUT COOLANT AND
STEAM AND THE PRESSURE DROPS CONTINUE
SERVICE.
WARNING: CONSTANT TENSION HOSE CLAMPS
ARE USED ON MOST COOLING SYSTEM HOSES.
WHEN REMOVING OR INSTALLING, USE ONLY
TOOLS DESIGNED FOR SERVICING THIS TYPE OF
CLAMP. ALWAYS WEAR SAFETY GLASSES WHEN
SERVICING CONSTANT TENSION CLAMPS.
CAUTION: A number or letter is stamped into the
tongue of constant tension clamps. If replacement
is necessary, use only a original equipment clamp
with matching number or letter (Fig. 6).
The hose clamps are removed by using Special Tool
6094 or equivalent constant tension clamp pliers
(Fig. 7) to compress the hose clamp.
A hardened, cracked, swollen or restricted hose
should be replaced. Care should be taken not to dam-
age radiator inlet and outlet when removing hoses.
Radiator hoses should be routed without any kinks
and indexed as designed. The use of molded hoses is
recommended.Make sure hoses and connectors are clean and dry
before installation. Do not lubricate hoses when
installing.
Spring type hose clamps are used in all applica-
tions. If replacement is necessary, replace with the
original Mopartequipment spring type clamp.
WATER PUMP
The water pump has a diecast aluminum body and
housing with a stamped steel impeller. The water
pump bolts directly to the cylinder block and is
driven by the timing belt (Fig. 8). Cylinder block to
water pump sealing is provided by a rubber O-ring.
The water pump is the ªheartº of the cooling sys-
tem. It pumps the coolant through the engine block,
cylinder head, heater core, and radiator.
NOTE: The water pump on all models can be
replaced without discharging the air conditioning
system.
Fig. 6 Spring Clamp Size Location
1 ± SPRING CLAMP SIZE LOCATION
Fig. 7 Hose Clamp Tool
1 ± HOSE CLAMP TOOL 6094
2 ± HOSE CLAMP
Fig. 8 Water Pump
1 ± CYLINDER BLOCK
2 ± PUMP BODY
PLCOOLING SYSTEM 7 - 5
DESCRIPTION AND OPERATION (Continued)

AUTOMATIC TRANSMISSION OIL COOLER
Oil coolers are internal oil to coolant type, mounted
in the radiator lower tank (Fig. 9). Rubber oil lines
feed the oil cooler and the automatic transmission.
Use only approved transmission oil cooler hose. Since
these are molded to fit space available, molded hoses
are recommended. Tighten Oil Cooler Hose Clamps
to 2 N´m (18 in. lbs.).
ACCESSORY DRIVE BELTS
The accessory drive consist of two Poly-V type
drive belts (Fig. 10). One belt drives the generator,
the other drives the power steering pump and air
conditioning compressor (if equipped). The power
steering/air conditioning belt is tensioned by an auto-
matically controlled belt tensioner. The generator
belt is manually tensioned using an adjusting bolt
and a locking nut.
ENGINE BLOCK HEATER
The heater is mounted in a core hole (in place of a
core hole plug) in the engine block, with the heating
element immersed in coolant (Fig. 11). The engine
block heater is available as an optional accessory.
The heater is operated by ordinary house current
(110 Volt A. C.) through a power cord and connector
behind the radiator grille.
When in operation, the engine block heater can
provide easier engine starting and faster warm-up,
when vehicle is operated in areas having extremely
low temperatures.CAUTION: The power cord must be secured in its
retainer clips, and not positioned so it could con-
tact linkages or exhaust manifolds and become
damaged.
Fig. 9 Automatic Transmission Oil Cooler
1 ± CLAMPS
2 ± HOSES
Fig. 10 Accessory Drive Belts
1 ± GENERATOR BELT
2 ± AUTOMATIC BELT TENSIONER
3 ± POWER STEERING PUMP/A/C COMPRESSOR BELT
Fig. 11 Engine Block Heater
1 ± CORE PLUG
2 ± BLOCK HEATER
3 ± POWER CORD
7 - 6 COOLING SYSTEMPL
DESCRIPTION AND OPERATION (Continued)

DIAGNOSIS AND TESTING
COOLING SYSTEM DIAGNOSIS
CONDITION POSSIBLE CAUSE CORRECTION
TEMPERATURE GAUGE READS
LOW1. Has a Diagnostic Trouble Code
(DTC) been set indicating a stuck
open engine thermostat?1. Refer to On Board Diagnostic in
Group 25. Replace thermostat, if
necessary. If a (DTC) has not been
set, the problem may be with the
temperature gauge.
2. Is the temperature gauge (if
equipped) connected to the
temperature gauge coolant sensor
on the engine?2. Check the connector at the
engine coolant sensor. Refer to
Group 8E. Repair as necessary.
3. Is the temperature gauge (if
equipped) operating OK?3. Check Gauge operation. Refer to
Group 8E. Repair as necessary.
4. Coolant level low during cold
ambient temperature, accompanied
by poor heater performance.4. Check coolant level in the coolant
recovery/reserve container and the
radiator. Inspect the system for
leaks. Repair as necessary. Refer to
WARNINGS in this section before
removing pressure cap.
TEMPERATURE GAUGE READS
HIGH OR ENGINE COOLANT
WARNING LAMP ILLUMINATES.
COOLANT MAY OR MAY NOT BE
LOST FROM SYSTEM.1. Trailer being towed, a steep hill
being climbed, vehicle being
operated in slow moving traffic, or
engine idling during high ambient
(outside) temperatures with air
conditioning on. High altitudes
Could aggravate these conditions.1. This may be a temporary
condition and repair is not
necessary. Turn off the air
conditioning and drive the vehicle
without any of the previous
conditions. Observe the temperature
gauge the gauge should return to
the normal range. If the gauge does
not return to the normal range,
determine the cause of the
overheating and repair. Refer to
POSSIBLE CAUSES in this section.
2. Is temperature gauge (if
equipped) reading correctly?2. Check gauge. Refer to Group 8E.
Repair as necessary.
3. Is temperature warning lamp (if
equipped) illuminating
unnecessarily?3. Check warning lamp operation.
Refer to Group 8E. Repair as
necessary.
4. Coolant low in recovery/reserve
container and radiator?4. Check for coolant leaks and
repair as necessary. Refer to
Checking Cooling System for Leaks
in this section.
5. Pressure cap not installed tightly.
If cap is loose, boiling point of
coolant will be lowered. Also refer
to the following step 6.5. Tighten cap.
PLCOOLING SYSTEM 7 - 7

CONDITION POSSIBLE CAUSE CORRECTION
TEMPERATURE GAUGE READS
HIGH OR ENGINE COOLANT
WARNING LAMP ILLUMINATES.
COOLANT MAY OR MAY NOT BE
LOST FROM SYSTEM. (CONT.)6. Poor seals at radiator cap. 6. (a) Check condition of cap and
cap seals. Refer to Radiator cap
Inspection. Replace cap if
necessary.
(b) Check condition of filler neck. If
neck is bent or damaged, replace
neck.
7. Coolant level low in radiator, but
not in coolant recovery/reserve
container. This indicates the
radiator is not drawing coolant from
the coolant recovery/reserve
container as the engine cools. As
the engine cools, a vacuum is
formed inside the cooling system. If
the radiator cap seals are defective,
or the cooling system has a leak, a
vacuum cannot be formed.7. (a) Check condition of radiator
cap and cap seals. Replace cap if
necessary.
(b) Check condition of filler neck.
Replace if damaged.
(c) Check condition of hose from
filler neck to coolant container. It
should be tight at both ends without
any kinks or tears. Replace hose as
necessary.
(d) Check coolant recovery/reserve
container and hose for blockage.
Repair as necessary.
8. Freeze point of coolant not
correct. Mixture ratio may be too
rich.8. Check coolant concentration.
Refer to Coolant Concentration
Testing in this section. Adjust
glycol-to-water ration as required.
9. Coolant not flowing through
system.9. Check for coolant flow at filler
neck with some coolant removed,
engine warm, and thermostat open.
Coolant should be observed flowing
through filler neck. If flow is not
observed, determine reason for lack
of flow and repair as necessary.
10. Radiator or A/C condenser fins
are dirty or clogged.10. Clean obstruction from fins.
11. Radiator core is plugged or
corroded.11. Replace or re-core radiator.
12. Fuel or ignition system
problems.12. Refer to Fuel and Ignition
System groups for diagnosis. Also
refer to the appropriate Powertrain
Diagnostic Procedure manual.
13. Dragging Brakes. 13. Inspect brake system and repair
as necessary. Refer to Group 5,
Brakes for diagnosis.
14 Bug screen or other aftermarket
accessory is being used causing
reduced air flow.14. Remove bug screen or
accessory.
15. Thermostat partially or
completely closed. This is more
prevalent on high mileage vehicles.15. Check thermostat operation and
replace as necessary. Refer to
thermostat in this section for
procedure.
7 - 8 COOLING SYSTEMPL
DIAGNOSIS AND TESTING (Continued)